Commit 7dd1fcc2 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

perf_counter: provide pagefault software events 



We use the generic software counter infrastructure to provide
page fault events.

Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 15dbf27c

arch/powerpc/mm/fault.c

+3 −0
Original line number Diff line number Diff line
@@ -29,6 +29,7 @@ 
#include <linux/module.h>

#include <linux/kprobes.h>

#include <linux/kdebug.h>

#include <linux/perf_counter.h>



#include <asm/firmware.h>

#include <asm/page.h>
@@ -170,6 +171,8 @@ int __kprobes do_page_fault(struct pt_regs *regs, unsigned long address, 
		die("Weird page fault", regs, SIGSEGV);

	}



	perf_swcounter_event(PERF_COUNT_PAGE_FAULTS, 1, 0, regs);



	/* When running in the kernel we expect faults to occur only to

	 * addresses in user space.  All other faults represent errors in the

	 * kernel and should generate an OOPS.  Unfortunately, in the case of an

arch/x86/mm/fault.c

+3 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include <linux/tty.h>

#include <linux/smp.h>

#include <linux/mm.h>

#include <linux/perf_counter.h>



#include <asm-generic/sections.h>
@@ -1044,6 +1045,8 @@ do_page_fault(struct pt_regs *regs, unsigned long error_code) 
	if (unlikely(error_code & PF_RSVD))

		pgtable_bad(regs, error_code, address);



	perf_swcounter_event(PERF_COUNT_PAGE_FAULTS, 1, 0, regs);



	/*

	 * If we're in an interrupt, have no user context or are running

	 * in an atomic region then we must not take the fault:

kernel/perf_counter.c

+3 −50
Original line number Diff line number Diff line
@@ -1607,57 +1607,10 @@ static const struct hw_perf_counter_ops perf_ops_task_clock = { 
 * Software counter: page faults

 */



#ifdef CONFIG_VM_EVENT_COUNTERS

#define cpu_page_faults()	__get_cpu_var(vm_event_states).event[PGFAULT]

#else

#define cpu_page_faults()	0

#endif



static u64 get_page_faults(struct perf_counter *counter)

{

	struct task_struct *curr = counter->ctx->task;



	if (curr)

		return curr->maj_flt + curr->min_flt;

	return cpu_page_faults();

}



static void page_faults_perf_counter_update(struct perf_counter *counter)

{

	u64 prev, now;

	s64 delta;



	prev = atomic64_read(&counter->hw.prev_count);

	now = get_page_faults(counter);



	atomic64_set(&counter->hw.prev_count, now);



	delta = now - prev;



	atomic64_add(delta, &counter->count);

}



static void page_faults_perf_counter_read(struct perf_counter *counter)

{

	page_faults_perf_counter_update(counter);

}



static int page_faults_perf_counter_enable(struct perf_counter *counter)

{

	if (counter->prev_state <= PERF_COUNTER_STATE_OFF)

		atomic64_set(&counter->hw.prev_count, get_page_faults(counter));

	return 0;

}



static void page_faults_perf_counter_disable(struct perf_counter *counter)

{

	page_faults_perf_counter_update(counter);

}



static const struct hw_perf_counter_ops perf_ops_page_faults = {

	.enable		= page_faults_perf_counter_enable,

	.disable	= page_faults_perf_counter_disable,

	.read		= page_faults_perf_counter_read,

	.enable		= perf_swcounter_enable,

	.disable	= perf_swcounter_disable,

	.read		= perf_swcounter_read,

};



/*